The arrest of throat cancer in human patients frequently involves the surgical removal of the patient's larynx. The larynx constitutes the human voice box, and consists of several cartilages and membranes. It contains the vocal cords, the tension or position of which changes so that air which passes from the lungs to the mouth via the larynx can be made to produce different sounds of the voice. Another function of the larynx is to prevent food and liquids from entering the trachea, or wind pipe, during the act of swallowing. Located adjacent to and immediately behind the trachea, in the human throat, is the food pipe or esophagus, and both the trachea and the esophagus, of course, communicate with the mouth.